Gas pressure reducer and regulator



Aug- 14, 1951 w. TUTTLE GAS PRESSURE REDUCER AND REGULATOR Filed March31, 1948 t. l C U L FIG. 2

IE n l w T m on W M W /29 @/JL.y

TINE

Patented Aug. 14, 1951 UNITED STATES PATENT OFFICE (Granted `under the`act of .March 3, 1883, :as amended `April 30, 1928; 370 O. G. 757) 1Claim.

`The present invention relates .to the control of gas pressure, and moreparticularly to the reduction and regulation of air pressure from theflask of a torpedo.

Conventional regulators utilize a pilot valve to produce a controlpressure, which operates the main throttling means either as a `fixedreference or to vary in direct or inverse proportion to any variation ininlet or outlet pressure in order to control the main throttling valveas desired.

The difficulty of ,providing a regulator that can handle extreme inletpressure variations and extreme iiow variations is associated with theprovision of a pilot with a sensitive response which neither overcontrols nor under controls, to `avoid chatter and sluggishness,respectively, and which has a very low spring rate and minimum friction.Such an arrangement is likely to respond to resonance and set up extremepulsa-` tions that .destroy the accuracy of regulation.

The .present invention has for its principal object the lprovision of apilot valve and main valve in which the flows and forces are so balancedthat even with extreme inlet pressure and outlet flow variations thepilot valve substan-tially does not move at all, except an almostimperceptible amount to correct for any disturbances. Since the pilot inthe `arrangement to be described does not move appreciably, it `can bevery small and relatively rigid, hence `avoiding delicate, easilydisturbed construction-s.

Another `object of .the invention is the elimination of springs, whichmay change characteristics in time, `under prolonged stress.

Another object of the invention `is the provision of a more simpleconstruction, in which very `.close lits .and extreme accuracy yofmachining are not necessary to produce accurate reguf lation.

Another object of the invention is the provision of a compact unit,wherein the large coil springs used in most regulators are eliminated.

These and other objects of the invention will become apparent from thefollowing descriptionv when read in conjunction `with the accompanyingdrawings, in which:

Fig. l is a section of a regulator consisting of a main valve and apilot valve.

Fig. 2 `is a graph showing the relation of :the pressures in theregulator.

A body I of metal or similar material is provided w-ith a verticalcylindrical bore 2., 3. The bore has two portions, lthe lower 2 beingAof smaller diameter than the upper 3. The central exit recess 4 leadsto anoutlet 5. A piston B is. adapted to `move Verticallyinthebore 2,3.The.

` piston '6 comprises a seat I at its lower end,

a tapered throttling portion 8 above the seat 1, a reduced stem portion9, a plurality of .guides lill and Iii, and a piston `head I2 providedwith aseal l I2', as will be more fully described hereinafter.

The piston head I2 is of slightly greater diameter than that of the seatl. Extending axially through the piston j6 from the seat l to almostthrough the head I2 is a gas passage I3 and a restricted opening I 4leads from the upper end of the passage I3 to the top of the head I2.

Gas from a reservoir is designed to enter the regulator through an inletI6 and move the piston 5 upwardly until the seat 1 rests against ashoulder I'I of the body I. The guides I0 and II center the piston 6during its movement in the bore 2, 3.

Above the head I2 and spaced there-from is ia rigid plate I8, so thatthe enclosed space lconstitutes a control chamber I9. At its center, theplate I8 is provided with a small raised valve seat 2I containing asmall port 22. The plate I8 is secured in position by a cap 23 threadedto the body I and sealed by a gasket 25. The cap 23 is internallythreaded to hold a hollow bushing 26 at its upper end. At the bottom ofthe bushing 26 is an elastic diaphragm 21 that is adapted normally tobear against the port 22 to close the latter, the spacebetween thediaphragm 2l and the rigid plate IB constituting a shallow cha-mber 28.The bushing 26 may be sealed with a gland'29.

The cap 23 contains a recess 3| leading tothe chamber 28. Within thebody I and extending vertically'thereof, to one side of the bore 2;, v3,is a passage 32 connecting the recess 3| with the exit recess 4. Thepassage 32 is of sufcient size so that the pressures in the chamber 28and the exit recess# are substantially equal.

When high pressure gas enters through the inlet I6, it moves the piston6 upwardly until the upper portion oi the seat 'I rests against theshoulder I'I of the body I. The gas will now pass through the passage I3and the restricted opening I4 into the control `chamber I9, where thepressure rises until it reaches a value slightly below the incomingpressure. Because of the difference in cross section of the piston headI2 and the seat l, the piston B will have more force.

exerted on it in a downward direction than in an upward, and as a resultthe piston 6 will be,

moved downwardly. When this happens, gas from the inlet I6 will iiowinto the exit recess l and through the passage 32 into the chamber 2.8under the diaphragm 27,. In this chamber 28the pressure 'will buildup`until itis of suf@` icient magnitude to overcome the initial force ofthe diaphragm 21 on the port 22 and to move the centerof the diaphragm21 slightly upward away from the port 22. The gas will now ow from `thecontrol chamber I9 through the port 22 and through the recess 3| and thevertical passage 32 to the exit recess 4. This flow is not sufficient toalter-the substantially Yequal pressures in the chamber 28 and the exitrecess 4. As the gas passes through the small space between the rim ofthe port 22 and the Vdiaphragm 21, it tends to lower the pressure in thecontrol chamber I9. Equilibrium is established when the desired outletpressure in the outlet 5, determined by the position of the bushing 26,has been reached in the exit recess 4. The port 22 and the diaphragm 21amount, therefore, to a pilot valve for controlling the pressure in the'mainl valve of the regulator.

The basic feature of the invention is in the relationship of thedifferential areas of the top and bottom portions of the piston 6. Whenthese .proportions are properly chosen, the position of the diaphragm 21for various inlet pressures is always the same. Consequently, the pilotvalve, comprising the port 22 and the diaphragm 21, can be small andrelatively rigid, without introducing error into the regulation. Thetendency to hunt or overcontro is avoided, because the comparativerigidity of the elastic member 21 and the high damping effect of itsbearing at its outer edge prevent resonant conditions and do notintroduce friction errors that would otherwise be present if thediaphragm 21 had to move when the inlet pressure or flow changed. Thefact that the diaphragm 21 does not move, once it has attained itsequilibrium position, eliminates several errors inherent in conventionalregulators due to springs, friction, oVersensi-tivity and resonance. Inthe preferred embodiment, the tapering portion 8 of the piston 6requires a large movement of the piston 6 for a change in inlet pressureor flow. This further tends to .prevent pressure oscillation due toexternal vibration. It should be noted that any friction of the seal I2is completely neutralized by the control pressure in the control chamberI9 produced by the position of the diaphragm 21.

The following is a demonstration of the relationship between thediameters of the bore 2 and the bore 3 to produce a constant spacingbetween the diaphragm 21 and the rim of the port 22 for a iixed outletpressure.

Y Since Pi-I-Pc are the only variables, this may be writteny PC=P1 aconstant If the inlet pressure falls, the relationship will .be such asshown in Fig. 2. Now the flow through the restricted opening I4 and thepilot valve formed by the port 22 and the diaphragm 21 must be equal in.pounds per second. The ow through the opening I4 is dependent upon thediierence between P1 and Pc and the density at P1. The ilow through thepilot valve is dependent upon the diierence between Pc and K and thedensity at Pc. If Pc were near K, the ilow through the por-t 22 wouldvary Widely, and the flow through the pilot valve would requireconsiderable movement of the diaphragm 21. As Pe is made nearer to P1 byreducing the difference in area between the cylindrical bore portion 2and the cylindrical bore portion 3, the variation in flow through theport 22 is reduced, and therefore the required variation in opening ofthe pilot valve from Ithis cause is reduced. At the same time, the flowthrough the pilot valve when P1 is high is also high because of thelarge differential between Pc and K, and is low when P1 is low becauseof the small differential between Pc and K. In the extreme oase, with Pcvery close to P1, the pilot valve would actually have to open wider asP1 decreased. Hence, there is an optimum ratio nbetween the diameters 2and 3 where the pilot valve spacing or opening remains constant, therequired variation in ilow being caused exactly by the variation in thedifference in .pressure between Pc and K. In an actual test case, theproportions were as follows:

P1: 3000 to 500 p. s. i.

Pc: 2800 to 500 p. s. i.

K: 500 p. s. i.

Diam. of restricted opening I4: 0.015

Diam. of port 22: 0.020" Y Diam. of upper cylindrical bore portion 3 ofmain valve: 0.957"

e Diam. of lower cylindrical bore portion 2 of main valve: 0.937

Position of diaphragm 21 off seat 2I: 0.001 Movement of diaphragm 21:less than 0.0001

Variation of K: il p. s. i. It was a rise of `2vk p. s. i. due to thehigh control pressure variation acting on the small area of thediaphragm 21 directly over the 0.015 diameter opening I4. This could becompensated by using a Very slightly smaller diameter for the lowercylindrical boreA other than disclosed; or a poppet or diaphragm valvemay be used as the main valve so long as' a control chamber is includedin which control pressure is of such a function of the inlet pres' sureas to result in zero movement of the pilot valve.

The invention herein described may be manufactured and used by or forthe Governmentof the United States of America forV governmental purposeswithout the payment of any royaltiesv thereon or therefor. i

What is claimed is:

In a iluid pressure regulator, an elongated cylindrical housing providedwith coaxial bores de. lining a high pressure chamber at one end of thehousing for connection to a fluid pressure supply source, a cylindricalcontrol chamber spaced fromsaid'high pressure chamber and terminatingvat the other end of the housing in an annular recess, a lowrpress'urechamber between said high pressure chamber and said control chamber andprovided with an outlet, a rigid plate removably fitted in said annularrecess and provided with an orifice extending therethrough from saidcontrol chamber and terminating in a raised seat, a piston valvereciprocable axially of said housing and including a Valve portioncontrolling now from said high pressure chamber to said low pressurechamber, said valve portion having an effective area exposed to fluid inthe high pressure chamber for urging the valve toward a closed position,a piston portion having an effective area greater than that of saidValve portion and exposed to fluid in the control chamber for urging thevalve into an open position, and a stem portion connecting said Valveportion and said piston portion, said piston Valve being provided withan axial passageway conducting fluid at a restricted rate from said highpressure chamber to said control chamber, a bonnet sealing said housingat its end adjacent said plate, a bushing threaded into said bonnet andterminating at its inner end in an annular recess, a

flexible diaphragm fitted in said bushing recess in spaced relation tosaid plate and normally resiliently contacting said raised seat, thespace between said diaphragm and plate constituting a pilot valvechamber, said diaphragm having an effective area exposedto fluid in thepilot valve chamber for urging the diaphragm away from said seat to opensaid pilot Valve, and means conducting uid from said pilot valve chamberto said low pressure chamber.

WAINWRIGHT TUTTLE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 213,118 Locke Mar. 11, 1879873,324 Michaels Dec. 10, 1907 1,098,616 Creveling June 2, 19141,944,424 Fleeson Jan. 23, 1934 2,015,915 Adsit Oct.. 1, 1935 2,471,294Watts May 24, 1949

